Leukocyte infiltration into inflammatory sites is believed to be regulated by 8-10 kD proteins known as chemokines. These chemokines are classified into four groups, depending on the spacing of their N-terminal cysteine residues, designated CC, CXC, XC and CX3C. Chemokines can mediate a range of proinflammatory effects on leukocytes, such as triggering of chemotaxis, degranulation, synthesis of lipid mediators, and integrin activation (Oppenheim, J. J. et al., Annu. Rev. Immunol., 9:617-648 (1991); Baggiolini, M., et al., Adv. Imunol., 55:97-179 (1994); Miller, M. D. and Krangel, M. S., Crit. Rev. Immunol., 12:17-46 (1992)).
One chemokine, Monocyte Chemotactic Protein 1 (MCP-1), also known as CCL2, acts upon monocytes, lymphocytes and dendritic cells, to induce chemotaxis, granule release, respiratory burst and cytokine release. Studies have suggested that MCP-1 is implicated in the pathology of diseases such as rheumatoid arthritis, atherosclerosis, granulomatous diseases, chronic obstructive pulmonary disease (COPD), obesity/diabetes, neuropathic pain, cancer, and multiple sclerosis (Koch, J. Clin. Invest. 90:772-79 (1992); Hosaka et al., Clin. Exp. Immunol. 97:451-457 (1994); Schwartz et al., Am. J. Cardiol. 71(6):9B-14B (1993); Schimmer et al., J. Immunol. 160:1466-1471 (1998); Flory et al., Lab. Invest. 69:396-404 (1993); Gong et al., J. Exp. Med. 186:131-137 (1997); Salcedo et al. Blood 96(1) 34-40 (2000); Bracke et al., Inflammation & Allergy—Drug Targets 6: 75-79 (2007); Chung Current Drug Targets—Inflammation & Allergy 4: 619-625 (2005).
CCR2 is a seven-transmembrane domain G-protein coupled chemotactic receptor which binds MCP-1 as well as other chemokines including CCL8 (MCP-2), CCL7 (MCP-3) and CCL13 (MCP-4) (Charo, I. F., et al., Proc. Natl. Acad. Sci. USA 91:2752-2756 (1994); Myers, S. J., et al., J. Biol. Chem. 270:5786-5792 (1995); Gong et al., J. Biol Chem 272:11682-11685 (1997); Garcia-Zepeda et al., J. Immunol. 157:5613-5626 (1996)). CCR2 is also known as CMKBR2 and CKR2. Two alternatively-spliced forms of the CCR2, CCR2A and CCR2B, have been cloned which differ in their C-termini (Wong et al (1997) J. Biol. Chem. 272:1038-1045). In signaling studies, both CCR2A and CCR2B mediate agonist-dependent calcium mobilization and adenylyl cyclase inhibition. CCR2 is expressed on monocytes, T cells, and dendritic cells, and interacts with chemokines secreted by endothelial cells, monocytes, and synovial fibroblasts.
The biological role of CCR2 has been probed through the use of CCR2 knockout mice (Boring et al., J Clin Invest. 100(10):2552-61 (1997); Boring et al., Nature 394(6696):894-7 (1998); De Paolo et al., J Immunol. 171(7):3560-7 (2003); Gaupp et al., Am J Pathol. 162(1):139-50 (2003)). CCR2−/− mice have significant defects in both delayed-type hypersensitivity responses and production of Th1-type cytokines, and are generally less susceptible to developing experimental autoimmune encephalomyelitis (EAE). In addition to modulating immune responses, CCR2 is a co-receptor for HIV (Connor et al., J. Exp. Med. 185:621-628 (1997); Frade et al., J Clin Invest. 100(3):497-502 (1997)).
Due to the involvement of MCP-1 and its receptor CCR2 in undesirable immune responses, CCR2 antagonists may be promising therapeutic agents. However, few CCR2 antagonists have been described (see Ogilvie et al., Blood 97(7):1920-4 (2001)). Thus, there is a need for novel and improved compositions that will bind CCR2 and block CCR2 signaling mediated by its ligand.